Multi-premixer fuel nozzle

ABSTRACT

The present application provides a fuel nozzle for use in a gas turbine. The fuel nozzle may include a mounting flange, a number of premixers attached to each other, and a number of gas pathways extending from the mounting flange to the number of premixers.

TECHNICAL FIELD

The present application relates generally to gas turbine engines andmore particularly relates to the use of fuel nozzles with one fuelsupply and mounting column and multiple premixers for premixing prior tocombustion.

BACKGROUND OF THE INVENTION

Current fuel nozzle designs for gas turbine combustion systems generallyinclude one central mounting and fuel supply center body per fuel nozzleor a separate fuel supply. Several fuel and air circuits may becontained within the center body. When the fuel nozzle counts is in therange of about four to six nozzles, current combustion chambers with thecenter bodies generally present no problem from the standpoint ofdistributing airflow to the more central nozzles.

As the fuel nozzle count increases, however, the center bodies begin torestrict airflow to the more central nozzles. This restriction may causeunacceptable variations in the airflow uniformity between the center andouter fuel nozzles and between adjacent nozzles. This variation maycause uneven fuel air mixing and may result in decreased flame holdingmargins and non-uniform flame temperatures within the within thecombustion chamber. Further, these uneven temperatures may lead toincreased emissions and durability concerns.

There is thus a desire therefore for a gas turbine combustion systemwith more even airflow distribution about the center and the outernozzles, regardless of the nozzle count. Such a combustion system shouldmaintain reduced emissions while providing flame holding margins and lowcombustion dynamics response over a variety of operating conditions.

SUMMARY OF THE INVENTION

The present application thus provides a fuel nozzle for use in a gasturbine. The fuel nozzle may include a mounting flange, a number ofpremixers attached to each other, and a number of gas pathways extendingfrom the mounting flange to the number of premixers.

The present application further provides a combustion chamber. Thecombustion chamber may include a center nozzle with a fuel passage and apremixer and a number of outer nozzles. Each of the outer nozzles mayinclude a number of fuel passages and a number of premixers.

The present application further provides a fuel nozzle for use in a gasturbine. The fuel nozzle may include a mounting flange, a number ofpremixers attached to each other, a number of gas tubes extending fromthe mounting flange to the premixers, and an outer shell surrounding thefuel tubes.

These and other features of the present application will become apparentto one of ordinary skill in the art upon review of the followingdetailed description when taken in conjunction with the several drawingsand the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a gas turbine engine.

FIG. 2 is a perspective view of a known standard single center body fuelnozzle.

FIG. 3 is a perspective view of a known combustion chamber with a numberof nozzles having a single premixer per center body.

FIG. 4 is a perspective view of a multiple premixer fuel nozzle as isdescribed herein.

FIG. 5 is a perspective view of a combustion chamber with a number ofnozzles having multiple premixers per center body as is shown in FIG. 4.

FIG. 6 is side cross-section view of an alternative embodiment of amultiple premixer fuel nozzle as is described herein.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numbers refer to likeelements throughout the several views, FIG. 1 shows a schematic view ofa gas turbine engine 10. As is known, the gas turbine engine 10 mayinclude a compressor 20 to compress an incoming flow of air. Thecompressor 20 delivers the compressed flow of air to a combustor 30. Thecombustor 30 mixes the compressed flow of air with a compressed flow offuel and ignites the mixture. (Although only a single combustor 30 isshown, the gas turbine engine 10 may include any number of combustors30.) The hot combustion gases are in turn delivered to a turbine 40. Thehot combustion gases drive the turbine 40 so as to produce mechanicalwork. The mechanical work produced in the turbine 40 drives thecompressor 20 and an external load 50 such as an electrical generatorand the like. The gas turbine engine may use natural gas, various typesof syngas, and other types of fuels.

Other types of gas turbine engines 10 may be used herein. The gasturbine engine 10 may have other configurations and may use other typesof components. Multiple gas turbine engines 10, other types of turbines,and other types of power generation equipment may be used hereintogether.

FIG. 2 shows a known fuel nozzle 100. Generally described, the fuelnozzle 100 may include a flange 110 on one end that leads to a premixer115. The nozzle 100 may include a center body tube 120 that extends fromthe flange 110 and through the premixer 115. Positioned within thecenter body tube 120 may be a purge air pathway 130 extendingtherethrough. A number of fuel pathways 140 may encircle the purge airpathway 130 and may extend from the flange 110 through the center bodytube 120. The fuel nozzle 100 also may include a swirler 150 positionedwith the center body tube 120 of the premixer 115. The swirler 150 mayextend from the center body tube 120 to a burner tube 160. The swirler150 may include a number of vanes 170. The fuel pathways 140 may extendfrom the flange 110 through the center body tube 120 in-part and mayexit via the vanes 170 of the swirler 150. The premixer 115 of the fuelnozzle 100 also may include an inlet section 190 for the admission ofair through the swirler 150. Other configurations of the fuel nozzle 100and the components thereof may be used herein.

In use, gas may enter the flange 110, pass into the premixer 115, andexit from the vanes 170 of the swirler 150. The gas flow may mix with anincoming airflow from the inlet section 190. The gas and air flows thusmay mix within the premixer 115 and then may be ignited downstream ofthe fuel nozzle 100.

As is shown in FIG. 3, multiple fuel nozzles 100 may be mounted withinan end cover assembly 200 of a combustion chamber 205. As is shown, eachof the nozzles has a single fuel supply tube 210. The use of themultiple nozzles 100, however, may create a circuitous path 220 for theairflow, at least with respect to one or more center nozzles 230. Thisrestricted airflow between the center nozzles 230 and a number of outerfuel nozzles 240, however, may cause unacceptable variations in theairflow. These variations may cause uneven temperatures within thecombustion chamber 205 as a whole. As described above, these uneventemperatures may lead to increase emissions and durability concerns.

FIG. 4 shows a multiple premixer fuel nozzle 250 as is described herein.The multiple premixer fuel nozzle 250 also may include a flange 260leading to a center body tube 270. Likewise, a purge pathway 280 mayextend from the flange 260 and through the center body tube 270.Similarly, a number of fuel pathways 290 may extend from the flange 260and through the center body tube 270. Other configurations may be usedherein.

The multiple premixer fuel nozzle 250 may include a number of premixers300. Although three (3) premixers 300 are shown, any number of premixers300 may be used. Each premixer 300 may include a swirler 310 positionedtherein. As described above, each swirler 310 may include a number ofvanes 320. The fuel pathways 290 may pass through the flange 260,through the center body tube 270 in part, into each premixer 300, andexit about the vanes 320 of the swirler 310. Each premixer 300 also mayinclude a burner tube 335 positioned about the swirler 310 and an airinlet section 340 in a manner similar to that described above

In use, gas flows through the fuel pathways 290 and then into the vanes320 of the swirler 310 of each premixer 300. Likewise, air passesthrough the inlet sections 340 and the swirlers 310 so as to mix withthe gas within the burner tube 335. The mixed pathways are then igniteddownstream of the multiple premixer fuel nozzle 250.

FIG. 5 shows the use of the multiple premixer fuel nozzles 250 within acombustion chamber 350. As is shown, a single fuel nozzle 100 is used asa center nozzle 360 while a number of the multiple premixer fuel nozzles250 are used as a number of outer fuel nozzles 370. As is shown, thecombustor chamber 350 has a simplified airflow path 380 to the centernozzle 360 in particular. Specifically, the airflow path 380 may havefewer restrictions as compared to the design of FIG. 3. Further, lessrestricted air access also is available to the air inlet sections 340 ofeach premixer 300 of the outer fuel nozzles 370.

The use of the multiple premixer fuel nozzles 250 thus not only providesan even airflow distribution among the nozzles 100, 250 so as toincrease the overall efficiency of the gas turbine engine 10, but use ofthe multiple premixer fuel nozzles 250 also should provide a costreduction relative to the single center body designs of the fuel nozzles100. Moreover, the overall design of the combustion chamber 350 also maybe simplified.

FIG. 6 shows a cross-sectional view of an alternative embodiment of amultiple premixer fuel nozzle 400. Instead of use of the center bodytube 270, the multiple premixer fuel nozzle 400 may include a number offuel tubes 410 that extend from a flange 420 to a number of premixers430. The space between the flange 420 and the premixers 430 may beencased in an outer shell 440. The outer shell 440 provides structure inthe absence of the center body tube 270. The fuel tubes 410 thus may bemade out of flexible tubing as opposed to a structural member. Each fueltube 410 may be in communication with one of the premixers 430. Theflange 420 may include a number of apertures therein including a numberof fuel apertures 450 and air apertures 460. The fuel apertures 450 maybe in communication with the fuel tubes 410 while the air apertures 460may direct a flow of air towards each of the premixers 430. Otherconfigurations may be used herein.

The use of the multiple fuel tubes 410 thus allows a variable flow offuel to each of the premixers 430. Depending upon the nature of theload, steady state conditions, and transient conditions, varying theflow of fuel may be desired to each of the premixers 430.

It should be apparent that the foregoing relates only to certainembodiments of the present application and that numerous changes andmodifications may be made herein by one of ordinary skill in the artwithout departing from the general spirit and scope of the invention asdefined by the following claims and the equivalents thereof.

1. A fuel nozzle for use in a gas turbine, comprising: a mountingflange; a plurality of premixers attached to each other; and a pluralityof gas pathways extending from the mounting flange to the plurality ofpremixers.
 2. The fuel nozzle of claim 1, further comprising a centerbody in communication with the mounting flange.
 3. The fuel nozzle ofclaim 1, wherein the plurality of premixers each comprise a swirlertherein.
 4. The fuel nozzle of claim 3, wherein the plurality ofpremixers each comprise a burner tube downstream of the swirler.
 5. Thefuel nozzle of claim 3, wherein the swirler comprises a plurality ofvanes.
 6. The fuel nozzle of claim 5, wherein the plurality of gaspathways extend from the mounting flange to the plurality of vanes ofthe swirlers in the plurality of premixers.
 7. The fuel nozzle of claim1, wherein the plurality of premixers each comprise an air inletsection.
 8. The fuel nozzle of claim 2, wherein the center bodycomprises a plurality of pathways therethrough.
 9. The fuel nozzle ofclaim 1, wherein the plurality of gas pathways comprises a plurality offuel tubes.
 10. The fuel nozzle of claim 1, further comprising an outershell surrounding the plurality of fuel tubes.
 11. A combustion chamber,comprising: a center nozzle; wherein the center nozzle comprises a fuelpassage and a premixer; and a plurality of outer nozzles; wherein theplurality of outer nozzles comprises a plurality of fuel passages and aplurality of premixers.
 12. The combustion chamber of claim 11, whereinthe plurality fuel passages extend from a mounting flange to theplurality of premixers.
 13. The combustion chamber of claim 11, whereinthe plurality of premixers each comprise a swirler therein.
 14. Thecombustion chamber of claim 13, wherein the plurality of premixers eachcomprise a burner tube downstream of the swirler.
 15. The combustionchamber of claim 13, wherein the swirler comprises a plurality of vanes.16. The combustion chamber of claim 15, wherein the plurality of fuelpassages extend from a center body to the plurality of vanes of theswirlers in the plurality of premixers.
 17. The combustion chamber ofclaim 11, wherein the plurality of premixers each comprise an air inletsection.
 18. A fuel nozzle for use in a gas turbine, comprising: amounting flange; a plurality of premixers attached to each other; aplurality of fuel tubes extending from the mounting flange to theplurality of premixers; and an outer shell surrounding the plurality offuel tubes.
 19. The fuel nozzle of claim 18, wherein the plurality ofpremixers each comprise a swirler therein.
 20. The fuel nozzle of claim18, wherein the swirler comprises a plurality of vanes on communicationwith the plurality of fuel tubes.